how can I convert day of year to date in javascript?

Question

I want to take a day of the year and convert to an actual date using the Date object. Example: day 257 of 1929, how can I go about doing this?

Answer 1

You have a few options;

If you're using a standard format, you can do something like:

new Date(dateStr);

If you'd rather be safe about it, you could do:

var date, timestamp;
try {
    timestamp = Date.parse(dateStr);
} catch(e) {}
if(timestamp)
    date = new Date(timestamp);

or simply,    

new Date(Date.parse(dateStr));

Or, if you have an arbitrary format, split the string/parse it into units, and do:

new Date(year, month - 1, day)

Example of the last:

var dateStr = '28/10/2010'; // uncommon US short date
var dateArr = dateStr.split('/');
var dateObj = new Date(dateArr[2], parseInt(dateArr[1]) - 1, dateArr[0]);